noroot.xsl

<!-- Not displaying $root -->

<xsl:template match="page" mode="url">
	<xsl:apply-templates select="parent::page" mode="url"/>
	<xsl:value-of select="concat(@handle,'/')"/>
</xsl:template>

one.xsl

<!-- Displaying $root, in one template -->

<xsl:template match="page" mode="url">
	<xsl:apply-templates select="parent::page" mode="url"/>
	<xsl:if test="not(parent::page)">
		<xsl:value-of select="concat($root,'/')"/>
	</xsl:if>
	<xsl:value-of select="concat(@handle,'/')"/>
</xsl:template>

two.xsl

<!-- Displaying $root without the if -->

<xsl:template match="page" mode="url">
	<xsl:value-of select="concat($root,'/',@handle,'/')"/>
</xsl:template>

<xsl:template match="page/page" mode="url">
	<xsl:apply-templates select="parent::page" mode="url"/>
	<xsl:value-of select="concat(@handle,'/')"/>
</xsl:template>